U.S. patent application number 09/949606 was filed with the patent office on 2002-03-21 for controllable muffler system for internal combustion engine.
This patent application is currently assigned to CALSONIC KANSEI CORPORATION & NISSAN MOTOR CO., LTD.. Invention is credited to Horiuchi, Shinichi, Kaneko, Yukio, Kijima, Atsushi, Norikawa, Tanomo, Takeuchi, Kai.
Application Number | 20020033302 09/949606 |
Document ID | / |
Family ID | 26599662 |
Filed Date | 2002-03-21 |
United States Patent
Application |
20020033302 |
Kind Code |
A1 |
Kaneko, Yukio ; et
al. |
March 21, 2002 |
Controllable muffler system for internal combustion engine
Abstract
A controllable muffler system is sued for use with an engine
that produces a power by burning fuel. The system comprises a first
passage section extending from the engine for having an exhaust gas
of the engine flow therethrough. The first passage section has a
catalytic converter mounted thereon. The system further comprises a
dual passage section including second and third passage sections
which extend separately from an end of the first passage section.
The second passage has a control valve for controlling the flow
rate of the exhaust gas flowing therethrough. The system further
comprises a fourth passage section extending from respective ends
of the second and third passage sections to the open air. The
fourth passage section has a rear muffler mounted thereon. The
system further comprises a control unit which controls the control
valve of the second passage section in accordance with an operation
condition of the engine.
Inventors: |
Kaneko, Yukio; (Saitama,
JP) ; Norikawa, Tanomo; (Kanagawa, JP) ;
Horiuchi, Shinichi; (Kanagawa, JP) ; Takeuchi,
Kai; (Kanagawa, JP) ; Kijima, Atsushi;
(Kanagawa, JP) |
Correspondence
Address: |
Richard L. Schwaab
FOLEY & LARDNER
Washington Harbour
3000 K Street, N.W., Suite 500
Washington
DC
20007-5109
US
|
Assignee: |
CALSONIC KANSEI CORPORATION &
NISSAN MOTOR CO., LTD.
|
Family ID: |
26599662 |
Appl. No.: |
09/949606 |
Filed: |
September 12, 2001 |
Current U.S.
Class: |
181/232 ;
181/272; 181/275 |
Current CPC
Class: |
F01N 1/089 20130101;
F01N 1/165 20130101; F01N 1/166 20130101; F01N 1/10 20130101 |
Class at
Publication: |
181/232 ;
181/272; 181/275 |
International
Class: |
F01N 007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2000 |
JP |
2000-401412 |
Sep 11, 2000 |
JP |
2000-275072 |
Claims
What is claimed is:
1. A controllable muffler system for use with an engine that
produces a power by burning fuel, comprising: a first passage
section extending from said engine for having an exhaust gas of the
engine flow therethrough, said first passage section having a
catalytic converter mounted thereon; a dual passage section
including second and third passage sections which extend separately
from an end of said first passage section, said second passage
having a control valve for controlling the flow rate of the exhaust
gas flowing therethrough; a fourth passage section extending from
respective ends of said second and third passage sections to the
open air, said fourth passage section having a rear muffler mounted
thereon; and a control unit which controls said control valve of
the second passage section in accordance with an operation
condition of the engine.
2. A controllable muffler system as claimed in claim 1, in which at
least one of said second and third passage sections has a center
muffler mounted thereon.
3. A controllable muffler system as claimed in claim 2, in which
said center muffler is mounted on said second passage section, and
in which said control valve is positioned upstream of said center
muffler.
4. A controllable muffler system as claimed in claim 2, in which
said center muffler is mounted on said second passage section, and
in which said control valve is positioned downstream of said center
muffler.
5. A controllable muffler system as claimed in claim 2, in which
said center muffler is mounted on said third passage section.
6. A controllable muffler system as claimed in claim 1, in which
said second passage section is constructed to have a gas flow
resistance which is smaller than that of said third passage
section.
7. A controllable muffler system as claimed in claim 1, in which
said control unit controls said control valve in accordance with an
operation speed of said engine.
8. A controllable muffler system as claimed in claim 7, in which
said control unit closes said control valve when the engine is
under a low speed operation and opens said control valve when the
engine is under a middle/high speed operation.
9. A controllable muffler system as claimed in claim 1, further
comprises a front muffler which is mounted on the passage section
between said catalytic converter and an upstream end of said dual
passage section.
10. A controllable muffler system as claimed in claim 2, in which
said rear muffler of said fourth passage section comprises: a
cylindrical shell having front and rear ends closed; three
partition panels arranged in said cylindrical shell to define
first, second, third and fourth chambers in the same; two inlet
pipes each being inserted into the cylindrical shell and led to
said third chamber, the two inlet pipes being connected to the ends
of said second and third passages sections respectively; two outlet
pipes each extending through the cylindrical shell from said first
chamber to the open air; two inner pipes each extending between
said first and third chambers through said second chamber; and a
restricted opening formed in one of the partition panels to
communicate a restricted communication between said third and
fourth chambers.
11. A controllable muffler system as claimed in claim 10, further
comprising a plurality of small openings formed in given portions
of the two inlet pipes, two outlet pipes and two inner pipes, said
given portions being exposed to said second chamber thereby to
cause said second chamber to serve as a resonance chamber.
12. A controllable muffler system as claimed in claim 11, in which
said two outlet pipes have each a given portion wrapped with a
sound absorbing material, so that the given portions of the outlet
pipes serve as sound absorbing chambers.
13. A controllable muffler system as claimed in claim 2, in which
said second and third passage sections have respective center
mufflers mounted thereon, and in which said control valve is
positioned downstream of the center muffler of said second passage
section.
14. A controllable muffler system as claimed in claim 13, in which
the center muffler mounted on said second passage section
comprises: a cylindrical shell having front and rear ends closed;
apertured panels arranged in said shell; an inlet pipe extending
from the end of said first passage section, said inlet pipe being
inserted into the cylindrical shell from said front end and led to
a rear portion of the interior of said cylindrical shell to
constitute an expansion chamber therein; and an outlet pipe which
extends in the cylindrical shell from a front portion of the
interior of said cylindrical shell and is led to an upstream end of
said fourth passage section, said outlet pipe having an exposed
portion on which said control valve is mounted.
15. A controllable muffler system as claimed in claim 14, in which
said outlet pipe has a plurality of small openings at a given
portion exposed to a generally middle part of the interior of said
cylindrical shell.
16. A controllable muffler system as claimed in claim 15, in which
the center muffler mounted on said third passage section comprises:
a cylindrical shell having front and rear ends closed; a partition
panel installed in said cylindrical shell to define therein an
expansion chamber and a resonance chamber; apertured panels
arranged in said resonance chamber; an inlet pipe extending from
the end of said first passage section, said inlet pipe being
inserted into the cylindrical shell from said front end and led to
a rear portion of the interior of the cylindrical shell; and an
outlet pipe which extends in the cylindrical shell from a front
portion of said interior of the cylindrical shell and is led to the
upstream end of said fourth passage section.
17. A controllable muffler system as claimed in claim 16, in which
said inlet pipe has a plurality of small openings at a portion
exposed to said expansion chamber, and in which said outlet pipe is
formed at a given portion thereof with a plurality of openings
exposed to said resonance chamber, said given portion being wrapped
with a sound absorbing material, so that the given portion of the
outlet pipe serves as a sound absorbing chamber.
18. A controllable muffler system for use with an internal
combustion engine, comprising: a first passage section extending
from said engine for having an exhaust gas of the engine flow
therethrough, said first passage section having a catalytic
converter and a front muffler mounted thereon; a dual passage
section including second and third passage sections which extend
separately from an end of said first passage section, said second
passage having a control valve for controlling the flow rate of the
exhaust gas flowing therethrough; a fourth passage section
extending from respective ends of said second and third passage
sections to the open air, said fourth passage section having a rear
muffler mounted thereon; and a control unit which controls said
control valve of the second passage section in accordance with an
operation condition of the engine.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates in general to muffler systems
of an automotive engines, and more particularly to the muffler
systems of a controllable type that can control its sound muffling
or dampening performance in accordance with engine speed or the
like.
[0003] 2. Description of Related Art
[0004] In order to clarify the task of the present invention, some
known controllable muffler systems of the above-mentioned type will
be briefly described with reference to the accompanying
drawings.
[0005] In FIG. 8, there is shown one muffler system that is
described in Japanese Patent First Provisional Publication 4-72408.
The system of this publication generally comprises a chamber body
100A, an inlet pipe (no numeral) led into the chamber body 100A and
two outlet pipes 101 and 102 extending to the outside from the
interior of the chamber body 100A. The outlet pipe 101 is equipped
with a control valve 103 that is controlled in accordance with an
operation condition (e.g. engine speed) of an associated
engine.
[0006] In FIG. 9, there is shown another known muffler system that
Is described in Japanese Utility Model First Provisional
Publication 4-54917. The system of this publication generally
comprises a chamber body 100B and two inlet pipes 104 and 105 of
which upstream ends are mated. The inlet pipe 104 passes through
the chamber body 100B, having small openings thereof exposed to the
interior of the chamber body 100B, while the other inlet pipe 105
is led into a middle position of the chamber body 100B. The inlet
pipe 104 is equipped with a control valve 106 that is controlled in
accordance with an operation condition (e.g. engine speed) of an
associated engine.
[0007] Due to provision of the control valves 103 and 106, the
above-mentioned known muffler systems can exhibit optimum
performance in accordance with the engine operation condition.
However, increase in cost can not be avoided because of employment
of the control valves 103 and 106 which are actuated by complicated
electronic control systems.
[0008] In FIG. 10, there is shown still another known muffler
system that is described in Japanese Patent First Provisional
Publication 10-131738, which can be produced at relatively low
cost. The system generally comprises a chamber body 100C, an inlet
pipe, an outlet pipe and an inner pipe 107. The inner pipe 107 is
equipped at its downstream end with an exhaust pressure sensible
valve 108. That is, the valve 108 is controlled to open/close the
inner pipe 107 in accordance with a pressure difference created in
the chamber body 100C.
SUMMARY OF THE INVENTION
[0009] However, even the system of FIG. 10 tends to fail to exhibit
a satisfied performance because of the nature of the exhaust
pressure sensible valve 108. In particular, adjustment of the valve
108 for obtaining a desired muffling performance is difficult.
[0010] Accordingly, an object of the present invention is to
provide a controllable muffler system which is free of the
above-mentioned drawbacks.
[0011] According to the present invention, there is provided a
controllable muffler system which can be arranged entirely below a
vehicle floor to obtain an optimum controllable muffling
performance thereof.
[0012] According to a first aspect of the present invention, there
is provided a controllable muffler system for use with an engine
that produces a power by burning fuel, which comprises a first
passage section extending from the engine for having an exhaust gas
of the engine flow therethrough, the first passage section having a
catalytic converter mounted thereon; a dual passage section
including second and third passage sections which extend separately
from an end of the first passage section, the second passage having
a control valve for controlling the flow rate of the exhaust gas
flowing therethrough; a fourth passage section extending from
respective ends of the second and third passage sections to the
open air, the fourth passage section having a rear muffler mounted
thereon; and a control unit which controls the control valve of the
second passage section in accordance with an operation condition of
the engine.
[0013] According to a second aspect of the present invention, there
is provided a controllable muffler system for use with an internal
combustion engine, which comprises a first passage section
extending from the engine for having an exhaust gas of the engine
flow therethrough, the first passage section having a catalytic
converter and a front muffler mounted thereon; a dual passage
section including second and third passage sections which extend
separately from an end of the first passage section, the second
passage having a control valve for controlling the flow rate of the
exhaust gas flowing therethrough; a fourth passage section
extending from respective ends of the second and third passage
sections to the open air, the fourth passage section having a rear
muffler mounted thereon; and a control unit which controls the
control valve of the second passage section in accordance with an
operation condition of the engine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Other objects and advantages of the present invention will
become apparent from the following description when taken in
conjunction with the accompanying drawings, in which:
[0015] FIG. 1 is a diagram showing a controllable muffler system of
a first embodiment of the present invention;
[0016] FIG. 2 is an enlarged sectional view of an essential portion
of the controllable muffler system of the first embodiment;
[0017] FIG. 3 is a view similar to FIG. 1, but showing a second
embodiment of the present invention;
[0018] FIG. 4 is a view similar to FIG. 1, but showing a third
embodiment of the present invention;
[0019] FIG. 5 is a view similar to FIG. 1, but showing a fourth
embodiment of the present invention;
[0020] FIG. 6 is a view similar to FIG. 1, but showing a fifth
embodiment of the present invention;
[0021] FIG. 7 is a view similar to FIG. 1, but showing a sixth
embodiment of the present invention;
[0022] FIG. 8 is a sectional view of a first known controllable
muffler system;
[0023] FIG. 9 is a sectional view of a second known controllable
muffler system; and
[0024] FIG. 10 is a sectional view of a third known controllable
muffler system.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0025] In the following, the present invention will be described in
detail with reference to the accompanying drawings.
[0026] For ease of understanding, various directional terms such as
right, left, upper, lower, rightward and the like are used in the
description. However, such terms are to be understood with respect
to only a drawing or drawings on which the corresponding part or
portion is shown.
[0027] Referring to FIGS. 1 and 2, particularly FIG. 1, there is
shown a controllable muffler system 100 which is a first embodiment
of the present invention.
[0028] In the drawing, denoted by reference "E" is a V-type
internal combustion engine having two cylinder banks. As shown,
from the two cylinder banks of the engine "E", there extend
respective exhaust systems each generally comprising an exhaust
manifold 1a or 1b which directly extends from the cylinder bank, a
front tube 2a or 2b which extends from the exhaust manifold 1a or
1b and a catalytic converter 3a or 3b which is disposed on the
front tube 2a or 2b. This system is called "dual exhaust system"
and brings about a high engine performance because of a satisfied
lowering of exhaust interference.
[0029] As shown, downstream ends of the front tubes 2a and 2b are
united and led to an inlet of a front muffler 4. From an outlet of
the front muffler 4, there extends a rear tube 5. The rear tube 5
has a branched rear end 8 from which two tubes 6 and 7 extend
separately. The tubes 6 and 7 have first and second center mufflers
9 and 10 mounted thereon respectively. Rear ends of the tubes 6 and
7 are led to a rear muffler 11. As will be described in detail
hereinafter, the rear ends of the tubes 6 and 7 are respectively
connected to respective inlet pipes 13 and 14 of the rear muffler
11 and the rear muffler 11 has two tail pipes 45 and 46.
[0030] On the tube 6 downstream of the first center muffler 9,
there is mounted a butterfly valve 15 which is controlled by a
control unit 16. That is, the control unit 16 controls the
butterfly valve 15 in accordance with an engine speed. For this
controlling, the measures disclosed by Japanese Patent First
Provisional Publication 9-79051 or 7-91246 may be used. That is, in
the measure of the 9-79051 publication, an electric actuator driven
by a control signal is used for actuating the valve, while in the
measure of the 7-91246, a vacuum type actuator is used for
actuating the valve. That is, in the latter measure, by selectively
introducing a vacuum into the actuator from a vacuum tank which is
communicated with an intake manifold of the engine, the actuator
drives the valve.
[0031] Referring to FIG. 2, there is shown the detail of the first
and second center mufflers 9 and 10, the rear muffler 11 and the
connection therebetween.
[0032] As shown, the first center muffler 9 incorporated with the
butterfly valve 15 comprises a cylindrical shell 17. Front and rear
open ends of the shell 17 are closed by front and rear plates 18
and 19. Three apertured panels 23 are arranged in the shell 17 to
form a noise damping expansion chamber 20 in the shell 17. As
shown, an inlet pipe 21 extending from an upstream part of the tube
6 is inserted into the shell 17 from the front plate 18 and led to
the rightmost area exposed to the rear plate 19. While, an outlet
pipe 22 connected to a downstream part of the tube 6 is inserted
into the shell 17 from the rear plate 19 and led to the leftmost
area exposed to the front plate 18. The outlet pipe 22 is formed
with a plurality of small openings 22a exposed to a center area of
the noise damping expansion chamber 20. The inlet and outlet pipes
21 and 22 are held by the apertured panels 23.
[0033] The second center muffler 10 comprises a cylindrical shell
24 of which front and rear open ends are closed by front and rear
plates 25 and 26. A partition wall 27 is arranged in the shell 24
to define therein smaller and larger chambers which are an
expansion chamber 28 and a resonance chamber 29 respectively.
Within the larger resonance chamber 29, there are arranged two
apertured panels 23. As shown, an inlet pipe 30 extending from an
upstream part of the tube 7 is inserted into the shell 24 from the
front plate 25 and led to the resonance chamber 29. The inlet pipe
30 is formed with a plurality of small openings 30a exposed to the
expansion chamber 28. While, an outlet pipe 31 extending from a
downstream part of the tube 7 is inserted into the shell 24 from
the rear plate 26 and led to the expansion chamber 28. The outlet
pipe 31 is formed with a plurality of small openings at a portion
exposed to the resonance chamber 29, and the portion where the
small openings are formed is wrapped with a sound absorbing
material to constitute a sound absorbing chamber 32.
[0034] The rear muffler 11 comprises a cylindrical shell 33 of
which front and rear open ends are closed by respective plates 34
and 35. Three partition panels 36, 37 and 38 are arranged in the
shell 33 to define four chambers 39, 40, 41 and 42, which are a
first expansion chamber 39, a sound absorbing chamber 40, a second
expansion chamber 41 and a resonance chamber 42. The sound
absorbing chamber 40 has a sound absorbing material packed therein.
The two inlet pipes 13 and 14 extending from the tubes 6 and 7 are
inserted into the shell 33 from the front plate 34 and led to the
second expansion chamber 41. The inlet pipes 13 and 14 are formed
with a plurality of small openings 13a and 14a which are exposed to
the sound absorbing chamber 40, as shown.
[0035] Two outlet pipes 47 and 48 extending from the two tail pipes
45 and 46 are inserted into the shell 33 from the rear plate 35 and
led to the first expansion chamber 39. The outlet pipes 47 and 48
are formed with a plurality of small openings 47a and 48a which are
exposed to the sound absorbing chamber 40. Each of the outlet pipes
47 and 48 is formed, at a part thereof extending between the second
expansion chamber 41 and the resonance chamber 42, with a plurality
of small openings, and the portion where these openings are
provided is wrapped with a sound absorbing material to constitute a
sound absorbing chamber 49 or 50.
[0036] Within the rear muffler 11, there are further installed two
inner pipes 51 and 52 each extending between the first expansion
chamber 39 and the second expansion chamber 41 while passing
through the sound absorbing chamber 40. These inner pipes 51 and 52
are formed with a plurality of small openings 51a and 52a which are
exposed to the sound absorbing chamber 40. Furthermore, there is
installed another inner pipe 52 which is held by the partition
panel 38 and extends between the second expansion chamber 41 and
the resonance chamber 42. The partition panel 38 is formed with an
opening 54 through which the second expansion chamber 41 and the
resonance chamber 42 are connected.
[0037] In the rear muffler 11, the following dimensional relation
is established between the two inlet pipes 13 and 14 and the second
expansion chamber 41:
Expansion ratio=S.sub.41/(S.sub.13+S.sub.14) (1)
[0038] Wherein:
[0039] S.sub.41: sectional area of second expansion chamber 41,
[0040] S.sub.13: sectional area of first inlet pipe 13,
[0041] S.sub.14: sectional area of second inlet pipe 14.
[0042] In the following, operation of the above-mentioned
controllable muffler system 100 of the first embodiment will be
described.
[0043] As is described hereinabove, based on the engine speed, the
control unit 16 issues a control signal to control operation of the
butterfly valve 15.
[0044] Under Middle/High Speed Operation
[0045] When the engine speed increases to a middle or high level
thereby to increase the amount of exhaust gas, the control unit 16
controls the butterfly valve 15 to open the tube 6. With this, as
is seen from FIG. 1, the first center muffler 9 becomes
communicated with the rear muffler 11 through the tube 6.
[0046] Under this condition, the exhaust gas passing through the
catalytic converters 3a and 3b and the front muffler 4 is separated
into two streams at the rear end 8 of the rear tube 5, one being
directed toward the first center muffler 9 and the other being
directed toward the second center muffler 10. Due to the muffling
effect of the front muffler 4, first and second center mufflers 9
and 10 and rear muffler 11, noises of the exhaust gas from the
engine "E" are sufficiently dampened and the exhaust gas is
discharged to the open air from the tail pipes 45 and 46 of the
rear muffler 11.
[0047] As is described above, when the butterfly valve 15 is
opened, the exhaust gas from the front muffler 4 are permitted to
flow through two mutually independent exhaust passages each having
the first or second center muffler 9 or 10. That is, under this
condition, the exhaust flow passage extending from the front
muffler 4 increases its sectional area and thus induces reduction
in exhaust resistance. Thus, under the middle or high speed
operation, the engine "E" can exhibit a satisfied output
performance thereof. Furthermore, due to parallel usage of the two
center mufflers 9 and 10, the exhaust flow passage can exhibit a
satisfied muffling effect against the exhaust gas flowing
therethrough.
[0048] In the following, the detail of muffling effect of each
muffler 9, 10 or 11 will be described with reference to FIG. 2.
[0049] In the first center muffler 9, the exhaust gas passing
through the inlet pipe 21 is led into the expansion chamber 20 to
expand thereby to reduce or dampen the noises thereof.
[0050] In the second center muffler 10, the exhaust gas passing
through the inlet pipe 30 is led through the small openings 30a
into the expansion chamber 28 to reduce or dampen the noises
thereof, the exhaust gas passing through the inlet pipe 30 is led
into the resonance chamber 29 to reduce or dampen the noises
thereof, and at the same time, the exhaust gas from the expansion
chamber 28 is permitted to reduce or dampen the noises thereof
during passage of the sound absorbing chamber 32.
[0051] In the rear muffler 11, the exhaust gases passing through
the inlet pipes 13 and 14 are led into the second expansion chamber
41 to reduce or dampen the noises thereof.
[0052] Due to provision of the resonance chamber 42, the noises of
the exhaust gas led into the second expansion chamber 41 are
dampened. The exhaust gas is then led into the first expansion
chamber 39 through the two inner pipes 51 and 52 to further reduce
or dampen the noises thereof. During this, due to provision of the
small openings 51a and 52a of the pipes 51 and 52, the noises of
the exhaust gas are further dampened. The exhaust gas is then led
into the outlet pipes 47 and 48 to be discharged to the open air
through the tail pipes 45 and 46. During this, due to provision of
the small openings 47a and 48a and the sound absorbing chambers 49
and 50, the noise dampening of the exhaust gas is further
developed.
[0053] Under Low Speed Operation
[0054] When the engine speed reduces to a low level thereby to
decrease the amount of exhaust gas, the control unit 16 controls
the butterfly valve 15 to close the tube 6. With this, as is seen
from FIG. 1, the communication between the first center muffler 9
and the rear muffler 11 is blocked.
[0055] Under this condition, the exhaust gas from the front muffler
4 is permitted to flow through only the lower exhaust passage
including the tube 7 and the second center muffler 10. As shown in
FIG. 2, the exhaust gas from the tube 7 is led into the second
expansion chamber 41 through the second inlet pipe 14 and subjected
to the above-mentioned noise dampening. In addition to this, the
following additional effects are obtained.
[0056] Improved Noise Dampening
[0057] When the butterfly vale 15 is closed, the downstream part of
the tube 6 can act as an additional tubular branch of the rear
muffler 11. Thus, under this condition, due to addition of such
tubular branch, the rear muffler 11 can exhibit a noise dampening
effect against noises having specified frequencies. Furthermore,
under this condition, the chamber 20 of the first center muffler 9
can serve as a resonance chamber to dampen the noises of the
exhaust gas led toward the second center muffler 10. If the tube 6
is constructed to have a larger sectional area, low frequency
components of the noise of the exhaust gas can be effectively
dampened, which suppresses generation of undesired moaning effect
in the passenger cabin. Furthermore, the noise dampening effect is
much enhanced because of addition of the resonance chamber 20 at a
position remote from the rear muffler 11.
[0058] When practically used, the controllable muffler system 100
is entirely arranged below a floor panel of an associated motor
vehicle. Since the mufflers 9, 10 and 11 are each constructed
simple as is described hereinabove, they can be made compact and
thus, the layout of them under the floor panel can have a high
freedom.
[0059] When the butterfly valve 15 is closed, the following
advantageous phenomena are further obtained.
[0060] That is, under such condition, in the rear muffler 11, the
exhaust gas from the engine "E" is forced to flow through only the
inlet pipe 14 before reaching the second expansion chamber 41. That
is, under this condition, the Expansion ratio between the chamber
41 and an exhaust gas inlet passage (viz., the inlet pipe 14) is
twice as much as that between the chamber 41 and an exhaust gas
inlet passage (viz., both the inlet pipes 13 and 14), which
improves the noise dampening effect of the system 100.
[0061] In the first embodiment 100, the following modifications are
usable.
[0062] In the above description, the control unit 16 is described
to control the butterfly valve 15 in accordance with the engine
speed. However, if desired, the control of the butterfly valve 15
may be made in accordance with an accelerator angle of the vehicle,
or exhaust or intake pressure of the engine. That is, when the
accelerator angle, exhaust pressure or intake pressure (viz.,
absolute value of intake pressure) is large, the butterfly valve 15
is controlled to open, while when such factor is small, the
butterfly valve 15 is controlled to close.
[0063] Furthermore, if desired, the butterfly valve 15 may be
controlled like in the measures disclosed by Japanese Patent First
Provisional Publication 9-228819. That is, the open/close operation
of the valve 15 is controlled in accordance with an exhaust
pressure exerted in an upstream area of an exhaust pipe or a
negative pressure exerted in an intake manifold of the engine.
Furthermore, if desired, the butterfly valve 15 may be controlled
like in the measures disclosed by Japanese Patent First Provisional
Publication 10-131738. That is, for open/close operation, the
butterfly valve 15 is directly applied with an exhaust pressure
from the engine.
[0064] In the following, other embodiments of the present invention
will be described, in which substantially same parts as those of
the above-mentioned first embodiment 100 are denoted by the same
numerals, and detailed explanation of them will be omitted. That
is, only parts or portions which are different from those of the
first embodiment 100 will be described in detail for ease of
description.
[0065] Referring to FIG. 3, there is shown a controllable muffler
system 200 which is a second embodiment of the present
invention.
[0066] That is, in the second embodiment 200, there is no means
that corresponds to the first center muffler 9 used in the first
embodiment 100.
[0067] Thus, when the butterfly valve 15 is closed, the upstream
and downstream portions of the tube 6 with respect to the butterfly
valve 15 can serves as the above-mentioned side branches thereby to
effectively dampen the noises having specified frequencies. While,
when the butterfly valve 15 is opened, the tube 6 can serve as a
bypass passage for the center muffler 10 thereby to permitting the
engine "E" to produce a higher output power.
[0068] Due to removal of the first center muffler 9, the freedom in
positioning the butterfly valve 15 is improved thereby to much more
effectively dampen the low frequency components of noises of the
exhaust gas. Furthermore, due to removal of the muffler 9, the
entire arrangement of the system 200 can be compact in size and
thus mounting of the system 200 under the vehicle floor panel is
easily made.
[0069] Referring to FIG. 4, there is shown a controllable muffler
system 300 which is a third embodiment of the present
invention.
[0070] In the third embodiment 300, the butterfly valve 15 is
mounted on the tube upstream of the first center muffler 9.
[0071] That is, similar to the above-mentioned second embodiment
200, when the butterfly valve 15 is closed, the upstream and
downstream portions of the tube 6 with respect to the butterfly
valve 15 can serve as the above-mentioned side branches thereby to
effectively dampen the noises having specified frequencies. In this
third embodiment 300, substantially same advantages as those of the
first embodiment 100 are obtained. In addition, due to position
change of butterfly valve 15 relative to the first center muffler
9, the frequency of the noise effectively damped by the system 300
is changed.
[0072] Referring to FIG. 5, there is shown a controllable muffler
system 400 which is a fourth embodiment of the present
invention.
[0073] In this fourth embodiment 400, there is no means that
corresponds to the second center muffler 10 used in the first
embodiment 100.
[0074] Thus, when the butterfly valve 15 is closed due to low speed
running of the engine "E", the exhaust passage including the tube 7
can exhibit a sufficiently low exhaust pressure due to removal of
the center muffler 10 which would cause a certain resistance
against the exhaust flow therethrough. Thus, acceleration
performance of the engine "E" at the range of low and middle engine
speed is improved.
[0075] While, when the butterfly valve 15 is opened, the exhaust
passage including the tube 7 can serve as a bypass passage of the
other passage including the tube 6, the center muffler 9 and the
valve 15, which permits the engine "E" to produce a higher output
power.
[0076] Referring to FIG. 6, there is shown a controllable muffler
system 500 which is a fifth embodiment of the present
invention.
[0077] As is seen from the drawing, this fifth embodiment 500 is
substantially the same as the fourth embodiment 400 except that, in
the fifth embodiment 500, the throttle valve 15 is positioned
upstream of the center muffler 9. Thus, substantially same
advantages as those of the fourth embodiment 400 are obtained in
the fifth embodiment 500.
[0078] Referring to FIG. 7, there is shown a controllable muffler
system 600 which is a sixth embodiment of the present
invention.
[0079] In this sixth embodiment 600, there are no means that
correspond to the first and second center mufflers 9 and 10 used in
the first embodiment 100. That is, as is seen from the drawing, on
the tube 6, there is disposed only the butterfly valve 15, and on
the other tube 7, there is no device mounted thereon.
[0080] However, as is seen from the drawing, in this sixth
embodiment 600, the tube 6 has a sectional area larger than that of
the other tube 7.
[0081] Thus, when the butterfly valve 15 is closed due to low speed
running of the engine "E", the exhaust passage including the tube 7
can exhibit a sufficiently low exhaust pressure due to removal of
the center muffler 10 which would cause a certain resistance
against the exhaust flow therethrough. Thus, acceleration
performance of the engine "E" at the range of low and middle engine
speed is improved.
[0082] While, when the butterfly valve 15 is opened, the exhaust
passage including the tube 7 can serve as a bypass passage of the
other passage including the tube 61 and the valve 15, which permits
the engine "E" to produce a higher output power. Furthermore, since
the sectional area of the tube 7 is smaller than that of the other
tube 6, the tube 7 can have a much effective noise dampening
effect. That is, in system 600 of the sixth embodiment, the
difference between the pressure exerted when the butterfly valve 15
is opened and the pressure exerted when the valve 15 is closed can
be set relatively high.
[0083] In the foregoing description, the muffler system of the
invention has been described with respect to a V-type internal
combustion engine "E" having two cylinder banks. However, the
present invention is also applicable to an in-line type internal
combustion engine. That is, in this case, one of the two exhaust
lines from the engine "E" to the front muffler 4 is removed.
[0084] Furthermore, if desired, the front muffler 4 may be
removed.
[0085] Furthermore, if desired, the tubes 6 and 7 may be united at
their downstream portions. In this case, the rear muffler 11 (see
FIG. 2) needs only one inlet pipe led thereinto.
[0086] The entire contents of Japanese Patent Applications
2000-275072 (filed Sep. 11, 2000) and 2000-401412 (filed Dec. 28,
2000) are incorporated herein by reference.
[0087] Although the invention has been described above with
reference to the embodiments of the invention, the invention is not
limited to such embodiments as described above. Various
modifications and variations of such embodiments may be carried out
by those skilled in the art, in light of the above
descriptions.
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